Salinity is one of the most important factors that reduce the growth and antioxidant defense of plants. A controlled pot experiment was conducted to investigate the ameliorative effects of jasmonic acid (JA) priming (0, 5, and 10 mM) and humic acid (HA) (0, 3, and 6 g HA kg−1 soil) amendment on antioxidant enzymes and salt tolerance of forage sorghum seedling (Sorghum bicolor L.) grown under three salinity conditions (0, 100, and 200 mM NaCl). Salinity stress reduced emergence seedling index (ESI), promptness index (PI), emergence stress tolerance index (ESTI), dry weight stress tolerance index (DWSTI), and the activities of the peroxidase (POD) and catalase (CAT) enzymes. The activity of superoxide dismutase (SOD) and malondialdehyde (MDA) content increased with salinity. Application of JA positively affected all parameters except CAT and MDA. Humic acid significantly increased all measured parameters except ESTI, DWSTI, and SOD activity. At the 200 mM NaCl level, JA and HA increased CAT, POD, SOD, ESI, DWSTI, ESTI, PI, and MDA as compared with the control. The application of HA at 6 g kg−1 soil decreased SOD and ESI relative to the control at high salinity. The application of 10 mM JA combined with HA at 6 g kg−1 soil was most effective in alleviating salinity stress. Therefore, the combined application of JA and HA on forage sorghum may improve salt tolerance and increase antioxidant enzymes that alleviate damages caused by salinity stress. Core Ideas Application of jasmonic acid and humic acid (HA) mitigated salinity stress. Jasmonic acid (JA) and HA increased the antioxidant enzymes. Applying a combination of JA and HA at high levels of salinity improved salt tolerance.

Salinity is a major abiotic stress limiting crop growth and reducing grain yield. In recent years, little progress was made in salt‐tolerant cultivation techniques. Therefore, a controlled experiment was conducted to study the effects of nitrogen management (NM) on growth, antioxidant ability, and yield performance of salt‐tolerant rice (Oryza sativa L.) under salinity stress. Three salinity levels (0‰ as control; 0.75‰, 4.3 dS m−1; and 1.5‰, 7.7 dS m−1) and four levels of NM (tillering fertilizer/panicle initiation fertilizer = 7:3, 6:4, 5:5, and 4:6) were arranged in this study. Under salinity stress, plant height, tiller number, fresh weight, grain yield, panicle, spikelets per panicle, grain weight, and soluble sugar content in stem were significantly decreased. In contrast, antioxidant parameters of superoxide dismutase, peroxidase, and catalase were significantly increased. Grain filling percentage and sucrose content were slightly changed. Compared to the control, grain yield was reduced by 45.6%, 34.8%, 60.4%, and 46.7% at the ratio of 7:3, 6:4, 5:5, and 4:6 NM at 0.75‰ salinity level, and 73.5%, 59.7%, 74.8%, and 61.7% at 1.5‰ salinity level, respectively. The highest yield was generated by 6:4 NM at both the 0.75‰ and 1.5‰ salinity level, and the lowest by 4:6 and 5:5. However, NM could obviously alleviate the inhibition effects of salinity stress and improve antioxidant ability of rice. Among them, 6:4 NM performed the best alleviation effects, followed by 7:3 and 5:5 NM. This study suggests that the appropriate NM can effectively alleviate salinity stress and increase grain yield.

Seed priming is regarded as a beneficial and effective method enhancing performance of plants grown under stress conditions. This study illustrated the effect of four seed priming agents (2% H2O2, 52 mM NaCl, 50 mM KCl, 250 mM MgSO4) on two sorghum cultivars (Canada sorghum CFSH-30 and sorghum ‘1230’) grown in saline soils. Sorghum growth characteristics and biochemical parameters were investigated. Seed priming treatments alleviated the adverse effects of salt stress by decreasing MDA content and enhancing antioxidant enzymes (CAT, POD and SOD) activities and proline content, and hence increased sorghum fresh and dry weight. In terms of various parameters, sorghum ‘1230’ was more suitable to be grown in saline soil, and 52 mM NaCl and 50 mM KCl were the optimum priming agents to improve the performance of salt-stressed sorghum.

Castor bean (Ricinus communis L.), a promising bioenergy crop, is readily planted in marginal lands like saline soils. A controlled experiment was conducted to explore the possibility of using gibberellic acid (GA3) as a promoter for caster bean grown under NaCl conditions and to try to determine the most appropriate concentration of GA3 for seedling growth. The seeds of salt-tolerant cultivar Zibi 5 were firstly soaked with 0, 200, 250, and 300 µM GA3 for 12 h and then cultured with 1/2 Hoagland solution containing 0, 50, and 100 mM NaCl in pots filled with sand. Plant height, stem diameter, leaf area, dry mater of each organ, activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), soluble protein, and proline content in the leaves were examined. Plant height and stem diameter, SOD, and POD activity was significantly highest in the treatment of 250 µM GA3 under salt concentration of 50 mM NaCl among all the testing days; protein content was highest when GA3 concentration was 250 µM under 100 mM NaCl treatment. This indicated that caster bean seed soaking with 250 µM GA3 could be the most suitable concentration for promoting seedling growth of caster bean, improving their stress resistance.

BACKGROUND: Drought is the most serious limiting factor of rice production worldwide and is becoming more intensive with climate change in recent years. Screening and breeding drought-tolerant rice genotypes are essential to maintain yield gain and ensure food security under adverse environments. However, thus far, little attention has been given to the temporal changes of drought resistance concomitant with the year of release in rice genetic breeding. RESULTS: Sixteen rice genotypes bred or widely cultivated from 1934 to 2007 were grown in paddy fields (control) and upland fields (drought stress) to explore the variation of drought resistance in rice genotypes with the year of release. Grain yield and daily grain yield significantly increased with the year of release. The genetic improvements in the grain yield partially resulted from the significant increase in panicle, spikelets per panicle and filling percentage. In addition, various growth-related characteristics like biomass, harvest index, relative growth rate, grain density and growth duration increased with an increase of genetic refinement of the genotypes through the years, and they contributed to improvement of final rice yields. However, grain yield, yield components and these growth-related traits sharply declined under drought stress. Furthermore, the drought resistance coefficients of K Yield , K Daily grain yield , K Panicle number , K Spikelets per panicle , K Biomass , K Plant height , K Relative growth rate and K Filling percentage were prominently improved by genetic breeding. CONCLUSIONS: Drought resistance of rice genotypes has been significantly enhanced by genetic processes during the last 73 years in China, but they are still sensitive to drought conditions. Currently, there is still room for further improvement in drought resistance which is an important target in future breeding programs.Grain yield and DGY significantly increased with the year of release. The genetic improvements in grain yield partially resulted from the significant increase in panicles, spikelets per panicle and filling percentage. In addition, various growth-related characteristics like biomass, HI, RGR, grain density and growth duration increased with increase of genetic refinement of the cultivars through the years and they contributed to improvement of final rice yields. However, grain yield, yield components and these growth-related characteristics sharply declined under drought stress. Furthermore, the drought resistance coefficients of K Yield , K Daily grain yield , K Panicle number , K Spikelets per panicle , K Biomass , K Plant height , K Relative growth rate and K Filling percentage were prominently improved by genetic breeding. These results suggest that drought resistance of rice genotypes has been significantly enhanced by genetic processes during the last 73 years in China, but they are still sensitive to drought. Currently, the world is facing challenges from climate change and drought, and there is still room for further improvement in drought tole...